1. Field of the Invention
This invention relates to devices for providing support for biological tissue, for example to fuse vertebral bodies, repair herniated discs, and/or repair spinal compression fractures, and methods of using the same.
2. Description of Related Art
Some conditions of the spine result from degradation or injury to the bone structures of the spine, typically the vertebral body. These can be the result of bone degeneration such as through osteoporosis or trauma, such as compression fractures. breakdown or injury to the boney structures in the spine can result in pain and spinal deformity with comorbidities.
Vertebroplasty is an image-guided, minimally invasive, nonsurgical therapy used to strengthen a broken vertebra that has been weakened by disease, such as osteoporosis or cancer. Vertebroplasty is often used to treat compression fractures, such as those caused by osteoporosis, cancer, or stress.
Vertebroplasty is often performed on patients too elderly or frail to tolerate open spinal surgery, or with bones too weak for surgical spinal repair. Patients with vertebral damage due to a malignant tumor may sometimes benefit from vertebroplasty. The procedure can also be used in younger patients whose osteoporosis is caused by long-term steroid treatment or a metabolic disorder.
Vertebroplasty can increase the patient's functional abilities, allow a return to the previous level of activity, and prevent further vertebral collapse. Vertebroplasty attempts to also alleviate the pain caused by a compression fracture.
Vertebroplasty is often accomplished by injecting an orthopedic cement mixture through a needle into the fractured bone. The cement mixture can leak from the bone, potentially entering a dangerous location such as the spinal canal. The cement mixture, which is naturally viscous, is difficult to inject through small diameter needles, and thus many practitioners choose to “thin out” the cement mixture to improve cement injection, which ultimately exacerbates the leakage problems. The flow of the cement liquid also naturally follows the path of least resistance once it enters the bone—naturally along the cracks formed during the compression fracture. This further exacerbates the leakage.
The mixture also fills or substantially fills the cavity of the compression fracture and is limited to certain chemical composition, thereby limiting the amount of otherwise beneficial compounds that can be added to the fracture zone to improve healing. In an alternative procedure known as kyphoplasty, a balloon is first inserted in the compression fracture and the vertebra and is expanded to create a void before the cement is injected into the newly formed space.
A vertebroplasty device and method that eliminates or reduces the risks and complexity of the existing art is desired. A vertebroplasty device and method that may reduce or eliminate the need to inject a liquid directly into the compression fracture zone is also desired.
Other ailments of the spine result in degeneration of the spinal disc in the intervertebral space between the vertebral bodies. These include degenerative disc disease and traumatic injuries. In either case, disc degeneration can cause pain and other complications. Conservative treatment can include non-operative treatment requiring patients to adjust their lifestyles and submit to pain relievers and a level of underlying pain. Operative treatment options include disc removal. This can relieve pain in the short term, but also often increases the risk of long-term problems and can result in motor and sensory deficiencies resulting from the surgery. Disc removal and more generally disc degeneration disease are likely to lead to a need for surgical treatment in subsequent years. The fusion or fixation will minimize or substantially eliminate relative motion between the fixed or fused vertebrae. In surgical treatments, adjacent vertebra can be fixated or fused to each other using devices or bone grafts. These may include, for example, screw and rod systems, interbody spacers (e.g., PEEK spacers or allograft bone grafts) threaded fusion cages and the like.
Some fixation or fusion devices are attached to the vertebra from the posterior side. The device will protrude and result in additional length (i.e., needed to overlap the vertebrae) and additional hardware to separately attach to each vertebrae. Fusion cages and allografts are contained within the intervertebral space, but must be inserted into the intervertebral space in the same dimensions as desired to occupy the intervertebral space. This requires that an opening sufficient to allow the cage or graft must be created through surrounding tissue to permit the cage or graft to be inserted into the intervertebral space.
A spinal fixation or fusion device that can be implanted with or without the need for additional hardware is desired. Also desired is a fixation or fusion device that can be deployed in a configuration where overlapping the fixated or fused vertebrae is not required.
Also desired is an intervertebral device the may be inserted in to the intervertebral space at a first smaller dimension and deployed to a second, larger dimension to occupy the intervertebral space. The ability to insert an intervertebral spacer at a dimension smaller than the deployed dimension would permit less disruption of soft and boney tissue in order to access the intervertebral space.
An effective therapy for following up a discectomy is desired. A vertebral fusion technique that can be used subsequent to a discectomy is desired.